I just compile Allegro 4.2.1 and AllegroGL 0.4.1 with mingw32 3.4.2. I'm using MSVC8 so I built them with the "fix msvc8" command. I built a debug version as well. Instead of generating agl.lib and agld.lib, it generated agl_s.lib and agld_s.lib. (static?) Anyway, I linked to those libraries and I tried running this example provided with AllegroGL.

Because "system_driver" is a allegro variable initialized at allegro_init().Strange that examples work.Have you had any older version of allegrogl installed before? Maybe something is left and there are conflicts... just guessing.